JP2002255976A - Process for producing silicon compound bearing mercapto group - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an industrial process for producing the compounds represented by the following formula (I) (wherein X1 -X3 may be the same or different from each other and each H or a monovalent group in which at least one of them is hydrolyzable; R1 is a single bond or a divalent organic group) in high yield, while suppressing the decomposition during the purification, for example, distillation under reduced pressure and capable of markedly reducing the formation of distillation residue which is highly difficult to be disposed. SOLUTION: The reaction mixture including the compound of the following formula (I) as a result of the reaction is treated with anhydrous mineral acid and/or organic acid to adjust the pH to <=7 before the purification step.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a silicon compound having a mercapto group and a hydrolyzable group such as 3-mercaptopropylalkoxysilane useful as a silane coupling agent.

[0002]

BACKGROUND ART mercapto group in the molecule, as a method for producing a silicon compound having a hydrolyzable group, for example, in JP-A-8-291185, an alkali metal sulfide hydride of the general formula X (CH _{2) 3} Si (OR) _a R _3-a (X is C
represents 1 or Br, and R represents a methyl group, an ethyl group, or a propyl group, which may be the same or different. a represents an integer of 1, 2, or 3. ) Is reacted with 3-halopropylalkoxysilane in a sealed, pressurized and in the presence of an excess of hydrogen sulfide to obtain mercaptoalkoxysilane under mild conditions and suppressing by-products of sulfide compounds. A production method is described which is obtained at a high rate.

[0003]

However, according to this method, when the reaction solution was analyzed at the end of the reaction, 90%
Despite the high yield of the desired product,
When the target product is isolated by vacuum distillation as it is in the purification step, the target product is decomposed, the yield is reduced by 10% or more, and a large amount of difficult-to-treat distillation residue is generated. . The present invention eliminates the disadvantages of this method, and in order to mass-produce industrially, it is necessary to decompose a silicon compound having at least one mercapto group or hydrolyzable group in a purification step such as distillation under reduced pressure. It is an object of the present invention to provide a manufacturing method which suppresses post-processing and reduces the load on post-processing.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, after completion of the reaction, unreacted or excess alkali metal hydride in the reaction system is removed with mineral anhydride and / or Or, by treating with an organic acid, the decomposition of the target product during the purification step is suppressed, and as a result, it has been found that the amount of difficult-to-treat distillation residues can be significantly reduced,
The present invention has been completed.

That is, the present invention provides a method of formula (I)

Embedded image (Wherein, X _{1 to} X ₃ may be the same or different and are each hydrogen or a monovalent group, at least one of which represents a hydrolyzable group, and R ₁ is a single bond or a divalent group. In the method for producing a silicon compound represented by the formula (I), the reaction solution containing the formula (I) obtained by the reaction is treated with a mineral anhydride and / or an organic acid to adjust the pH to 7 or less. A production method characterized by performing a purification step, (2) a reaction solution containing a compound represented by the formula (I) obtained by the reaction is reacted with an alkali metal sulfide and a formula (II)

Embedded image (Wherein, X _{1 to} X ₃ and R ₁ represent the same meaning as described above;
Y represents a halogen atom. (1) The method according to (1), wherein the alkali metal sulfide is obtained by reacting an alkali metal alkoxide with hydrogen sulfide. The production method according to (2), wherein:
(4) After the reaction solution containing the compound represented by the formula (I) obtained by the reaction reacts the anhydrous alkali metal sulfide with hydrogen sulfide, the reaction solution containing the compound represented by the formula (II)

Embedded image (Wherein, X _{1 to} X ₃ , R ₁ , and Y represent the same meaning as described above), which is a reaction solution obtained by reacting a compound represented by the formula (1). Manufacturing method,
(5) The step of treating the reaction solution containing the formula (I) obtained by the reaction with a mineral anhydride and / or an organic acid to adjust the pH to 7 or less, wherein the pH is adjusted to 5 to 7 ( 1) The production method according to any one of (1) to (4),
(6) The method according to any one of (1) to (5), wherein the organic acid is a C1 to C6 organic acid.
(7) The method according to (6), wherein the C1 to C6 organic acid is formic acid or acetic acid.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. In the compound represented by the formula (I) to which the production method of the present invention is applied,
X _{1 to} X ₃ may be the same or different and are each a hydrogen or a monovalent group, and at least one of them represents a hydrolyzable group.

As the hydrolyzable group, no catalyst, an acidic catalyst such as hydrochloric acid, sulfuric acid, nitric acid, alkoxy zirconia and alkoxy titania, or a basic catalyst such as sodium hydroxide, ammonia and tetrahydroammonium hydroxide is used. Room temperature (25 ° C) in the presence of water
There is no particular limitation as long as the group can be hydrolyzed to generate a silanol group or a group capable of forming a siloxane condensate by heating within a temperature range of -100 ° C. Specifically, a hydrogen atom, carbon number 1
To 12 alkoxy groups, halogen atoms, amino groups and carboxyl groups.

More specifically, methoxy, ethoxy, propoxy, butoxy, phenoxybenzyloxy, methoxyethoxy, acetoxyethoxy, 2
-(Meth) acryloxyethoxy group, 3- (meth) acryloxypropoxy group, 4- (meth) acryloxybutoxy group, glycidyloxy group, epoxidized cyclohexylethoxy group, methyloxetanemethoxy group, ethyloxetanemethoxy group, oxacyclohexyl Siloxy group, fluorine, chlorine, bromine, iodine, amino group, dimethylamino group, diethylamino group, butylamino group, dibutylamino group, phenylamino group, diphenylamino group, acetoxy group, butyroyloxy group, etc. .
In addition, among the alkoxy groups having 1 to 12 carbon atoms, a methoxy group, an ethoxy group, a propoxy group, and a butoxy group are more preferable because the hydrolyzable group is particularly excellent in hydrolyzability.

When the functional groups X _{1 to} X ₃ include a non-hydrolyzable group, the non-hydrolyzable group includes a substituted or unsubstituted methyl group, ethyl group, propyl group, phenyl group and the like. No. In the formula (I), R ₁ represents a single bond or a divalent organic group. Specific examples include a substituted or unsubstituted methylene group, ethylene group, propylene group, butylene group and the like. Among these, a methyl group, an ethyl group, and a propyl group are more preferable because they are not bulky and do not inhibit hydrolysis of the hydrolyzable group more.

Specific examples of the compound represented by the formula (I) include a compound represented by the following formula.

[0011]

Embedded image

As the silane coupling agent, dialkoxysilane or trialkoxysilane is preferable, and trialkoxysilane is particularly preferable. As the non-hydrolyzable group, a methyl group or an ethyl group is preferable, and a methyl group is particularly preferable, from the viewpoint of reactivity and availability of raw materials.

In the compound represented by formula (II) used in the production of the present invention, X _{1 to} X ₃ and R ₁ have the same meanings as described above, and specific examples can be given. Y represents a halogen atom. As the compound represented by the formula (II), specifically, in specific examples of the compound represented by the formula (I),
Specific examples in which a mercapto group (SH group) is substituted with a halogen atom can be exemplified. Among the halogen atoms, a chloro atom and a bromo atom can be particularly preferably used.

Examples of the alkali metal hydride used in the present reaction include sodium hydrosulfide and potassium hydrosulfide. Industrially, sodium hydrosulfide is preferred. Sodium hydrosulfide may be produced outside the system or produced by reacting anhydrous sodium sulfide with hydrogen sulfide in the system, but usually hydrogen sulfide is added to the sodium alcoholate alcohol solution in the system. Injection can easily produce sodium hydrosulfide.

The alkali metal hydrosulfide is preferably used in an amount of 1 mol or more per 1 mol of the compound represented by the formula (II), and more preferably 1.03 to 1.25 mol. preferable.

The production of the compound represented by the formula (I) is preferably carried out in the presence of a solvent. Usable solvents include alcohol solvents such as methanol, ether solvents such as tetrahydrofuran, dioxane, and ethylene glycol dimethyl ether, benzene, xylene, and n-
Hexane, hydrocarbon solvents such as cyclohexane, and nitrile solvents such as acetonitrile can be exemplified,
These may be used alone or in combination of two or more, but are not particularly limited to these solvents.

As a reaction method for obtaining the compound represented by the formula (I), the production of 3-mercaptopropyltrimethoxysilane will be specifically described. In a pressure-resistant reaction vessel containing a solution of sodium bisulfide, hydrogen sulfide which is considered to be unnecessary for the original reaction is present in the system. Specifically, the reaction vessel is filled with hydrogen sulfide at 1.0 to 4.0 kg /
cm ² , preferably 2.0 to 4.0 kg / cm ² . This operation has the effect of suppressing the formation of sulfide bodies to about 1%, which was conventionally unavoidable in about 5 to 10%. In addition, since the reaction is carried out in a closed state, hydrolysis is not caused by water entering from the atmosphere to produce a polymer, and a high yield is obtained.

Next, 3-chloropropyl trialkoxysilane is gradually dropped into the reaction vessel over 1 hour, preferably 1 to 3 hours. Dropping 3-chloropropyl trialkoxysilane into sodium bisulfide works favorably in suppressing the formation of sulfides as by-products. Also, if the dropping time is 1 hour or more,
Similarly, the generation of a by-product sulfide can be suppressed. However, over 3 hours, there is not much improvement as compared to dropping in 3 hours.

After completion of the dropping of the 3-chloropropyl trialkoxysilane, the temperature is 70 ° C. or higher, preferably 90 ° C. or higher.
The reaction is completed below ℃. When the temperature is 70 ° C. or lower, it takes 5 hours or more to complete the reaction. Conversely, when the temperature is 120 ° C. or higher, a large load is applied to the pressure resistance of the apparatus.

In the present invention, after completion of the reaction, an alkali component such as an unreacted alkali metal hydride is treated with a water-free mineral acid or organic acid having a smaller pKa than that of hydrogen sulfide to adjust the pH to 7 or less. After that, a purification step such as distillation is performed.

When an acid containing water is used, the target compound represented by the formula (I) is hydrolyzed to produce a polymer, and the yield is reduced. As the acid used in the present invention, specifically, hydrogen chloride, hydrogen bromide, hydrogen chloride, hydrogen bromide, anhydrous mineral acids such as boric acid, formic acid, acetic acid,
Organic acids such as propionic acid, monochloroacetic acid, citric anhydride and tartaric acid can be exemplified.

As a treatment method using the above-mentioned acid, after the reaction is completed, the reaction solution is cooled, and the inside of the reaction vessel is returned to the atmospheric pressure. It is carried out by adding a water-free mineral acid or organic acid having a lower pKa than that of water. The amount to be added is pH
The amount is not particularly limited as long as it is 7 or less, but is preferably an amount until the alkali component and the acid component to be added are neutralized. If the pH is 7 or more, the effect of suppressing decomposition is small.

The method of detecting the neutralization point and the pH of the two may be determined by a pH meter or a conductivity meter using a non-aqueous pH electrode, or by using the alkali metal sulfide used and the formula (II). Can also be determined by stoichiometric calculation from the compound to be prepared. When using the desired compound represented by the formula (I) and an acid which can be separated by purification such as distillation, it can be used in a larger excess than required.

When the end point of neutralization is determined by a conductivity meter, the conductivity decreases as the alkali metal sulfide is neutralized, and the conductivity increases as the acid becomes excessive. Is measured, and the point at which the conductivity becomes minimum is defined as the end point. After completion of the neutralization, the salt formed in the reaction is filtered off, and the solvent is distilled off from the reaction solution. For example, the salt formed in the reaction is filtered off and then distilled under reduced pressure to obtain the desired formula (I) Can be obtained.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

[0026]

EXAMPLE 1 Anhydrous sodium sulfide 93.6 was placed in a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a gas injection tube.
g (1.2 mol). Furthermore, methanol 400
g was added to dissolve anhydrous sodium sulfide. At this time, heat was generated, and the internal temperature rose to about 60 ° C. After dissolution, 53.2 g (1.56 mol) of hydrogen sulfide was injected through a gas injection tube.
For 2 hours at a temperature of 30 to 40 ° C. Next, the reaction solution was placed in a 1-liter autoclave and heated until the internal temperature reached 70 ° C. The internal pressure at this time is 1.5
kg / cm ² . Here, 397.4 g (2.0 mol) of 3-chloropropyltrimethoxysilane was injected over 1 hour and reacted at 70 to 80 ° C. After injecting 3-chloropropyltrimethoxysilane, raise the temperature to 70-8.
Aged at 0 ° C. for 4 hours. After the reaction solution was cooled, the pressure was returned to the atmospheric pressure, and 30 g of hydrogen chloride gas was added to the reaction solution with stirring.
(0.8 mol) was blown slowly to neutralize. It was then filtered to remove sodium chloride. Here, when the filtrate was analyzed by gas chromatography, the product ratio was as shown below, and the generation of sulfide was very small. Ingredients composition ratio _{HS (CH 2) 3 Si (} OMe) 3 97.7% S {(CH2) 3 Si (OMe) 3} 2 2.3%

After methanol was distilled off from the filtrate, the residue was distilled under reduced pressure. As a result, 3-mercaptopropyltrimethoxysilane was obtained as a fraction having a pressure of 4 mmHg and a boiling point of 85 ° C.
2 g were obtained (yield 95.8%). The distillation residue was 16.5 g of a slightly viscous oil. There was no problem in extracting the distillation residue from the distillation flask.

Example 2 462.9 g (2.4 mol) of a 28% sodium methoxide methanol solution was placed in a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a gas injection tube. 88.5 g of hydrogen sulfide (2.6 m
ol) at a temperature of 30 to 40 ° C. over 4 hours. Next, the reaction solution was placed in a 1-liter autoclave and heated until the internal temperature reached 70 ° C. The internal pressure at this time was 1.5 kg / cm ² . Here, 397.4 g of 3-chloropropyltrimethoxysilane (2.0 mo)
1) was injected over 1 hour and reacted at 70 to 80 ° C. After injecting 3-chloropropyltrimethoxysilane, the mixture was aged for 3 hours while maintaining the temperature at 70 to 80 ° C. After cooling, the reaction solution was returned to atmospheric pressure, and adjusted to pH 5 with formic acid. The used formic acid was 27.6 g (0.6 mol). It was then filtered to remove sodium chloride. Here, when the filtrate was analyzed by gas chromatography, the product ratio was as shown below, and the generation of sulfide was very small. Ingredients composition ratio _{HS (CH 2) 3 Si (} OMe) 3 97.6% S {(CH 2) 3 Si (OMe) 3} 2 2.4%

After methanol was distilled off from the filtrate, the residue was distilled under reduced pressure. As a result, 3-mercaptopropyltrimethoxysilane was obtained as a fraction having a pressure of 4 mmHg and a boiling point of 85 ° C.
4 g were obtained (yield 95.6%). The distillation residue was 17.3 g of a slightly viscous oily substance. There was no problem in extracting the distillation residue from the distillation flask.

Example 3 303.8 g (1.58 mol) of a 28% sodium methoxide methanol solution was placed in a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a gas injection tube. 57.3 g of hydrogen sulfide (1.68
mol) was blown in at a temperature of 30 to 40 ° C. over 2 hours. Next, the reaction solution was placed in a 1-liter autoclave and heated until the internal temperature reached 70 ° C. The internal pressure at this time was 1.5 kg / cm ² . Here, 298.1 g of 3-chloropropyltrimethoxysilane (1.5 mol
1) was injected over 1 hour and reacted at 70 to 80 ° C. After injecting 3-chloropropyltrimethoxysilane, the mixture was aged for 1 hour while maintaining the temperature at 100 ° C. After the reaction solution was cooled, the pressure was returned to the atmospheric pressure, and formic acid was added dropwise while measuring the conductivity. The point at which the conductivity decreased and turned to an increase was defined as the neutralization end point. Formic acid used was 5.9 g (0.13 mol). It was then filtered to remove sodium chloride.
Here, when the filtrate was analyzed by gas chromatography, the product ratio was as shown below, and the generation of sulfide was very small. Ingredients composition ratio _{HS (CH 2) 3 Si (} OMe) 3 97.2% S {(CH 2) 3 Si (OMe) 3} 2 2.8%

After methanol was distilled off from the filtrate, distillation under reduced pressure resulted in 3-mercaptopropyltrimethoxysilane as a fraction having a pressure of 4 mmHg and a boiling point of 85 ° C.
7 g were obtained (95.3% yield). The distillation residue was 13.8 g of a slightly viscous oil. There was no problem in extracting the distillation residue from the distillation flask.

In a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a gas injection tube, 462.9 g (2.4 m) of a 28% methanol solution of sodium methoxide was placed.
ol) and 88.5 g of hydrogen sulfide from a gas injection tube
(2.6 mol) was blown in at a temperature of 30 to 40 ° C. over 4 hours. Next, the reaction solution was placed in a 1-liter autoclave and heated until the internal temperature reached 70 ° C. The internal pressure at this time was 1.5 kg / cm ² . Here, 3-
397.4 g of chloropropyltrimethoxysilane (2.
0 mol) over 1 hour and reacted at 70-80 ° C. After injecting 3-chloropropyltrimethoxysilane, the mixture was aged for 3 hours while maintaining the temperature at 70 to 80 ° C. After cooling, the reaction solution was returned to atmospheric pressure, and filtered to remove sodium chloride. Here, when the filtrate was analyzed by gas chromatography, the product ratio was as shown below, and the generation of sulfide was very small. Ingredients composition ratio _{HS (CH 2) 3 Si (} OMe) 3 97.6% S {(CH 2) 3 Si (OMe) 3} 2 2.4%

After methanol was distilled off from the filtrate, the residue was distilled under reduced pressure. As a result, 3-mercaptopropyltrimethoxysilane was obtained as a fraction having a pressure of 4 mmHg and a boiling point of 85 ° C.
8 g was obtained (83.5% yield). The distillation residue was 64.9 g of a mixture of a highly viscous oil and a fine white solid. It was very difficult to extract the distillation residue from the distillation flask.

[0034]

As described above, when the method of the present invention is used, decomposition during vacuum distillation is suppressed, and the desired silicon compound having a mercapto group and a hydrolyzable group is produced with high purity and high yield. In addition, it is possible to significantly reduce the amount of distillation residue that is difficult to process, and it is excellent as an industrial production method.

Claims (7)

[Claims] (1) Formula (I) (Wherein, X _{1 to} X ₃ may be the same or different and are each hydrogen or a monovalent group, at least one of which represents a hydrolyzable group, and R ₁ is a single bond or a divalent group. In the method for producing a silicon compound represented by the formula (I), the reaction solution containing the formula (I) obtained by the reaction is treated with a mineral anhydride and / or an organic acid to adjust the pH to 7 or less. A production method comprising performing a purification step. 2. A reaction solution containing a compound represented by the formula (I) obtained by the reaction is prepared by mixing an alkali metal sulfide with a compound of the formula (II). (Wherein, X _{1 to} X ₃ and R ₁ represent the same meaning as described above;
Y represents a halogen atom. 2. The method according to claim 1, wherein the reaction solution is obtained by reacting the compound represented by the formula (1). 3. The method according to claim 2, wherein the alkali metal sulfide is obtained by reacting an alkali metal alkoxide with hydrogen sulfide. 4. A reaction solution containing the compound represented by the formula (I) obtained by the reaction is obtained by reacting an anhydrous alkali metal sulfide with hydrogen sulfide, and then reacting with a compound of the formula (II). (Wherein, X _{1 to} X ₃ , R ₁ , and Y represent the same meaning as described above), which is a reaction solution obtained by reacting a compound represented by the following formula: Manufacturing method. 5. The process of treating a reaction solution containing the formula (I) obtained by the reaction with a mineral anhydride and / or an organic acid to adjust the pH to 7 or less, wherein the pH is adjusted to 5 to 7. The production method according to any one of claims 1 to 4, wherein: 6. The method according to claim 1, wherein the organic acid is a C1 to C6 organic acid. 7. The method according to claim 6, wherein the C1 to C6 organic acid is formic acid or acetic acid.